Though each MLS stadium has its X-factor—elevation, weather, playing surface—it’s often the 12th Man that makes a venue most challenging for the visitors.

MLSsoccer.com polled MLS players throughout the league to find out the 10 toughest venues to come out of with any points. Though the list is topped by a likely suspect, it’s who the players ranked second that may surprise you.

WHAT THE PLAYERS SAY

Kei Kamara, Sporting Kansas City: Seattle. They're fun. When they boo me, I love it. The atmosphere is really great out there. It's nice to play in that.

Jeff Larentowicz, Colorado Rapids: Toronto. They're so loud. They're always there. You always know at BMO that you're not only going up against the guys on the field, but also the energy they're getting from the crowd.

1. Qwest Field (Seattle Sounders)

Is there any way 36,000 fans can’t make a difference? When defenders can’t hear their 'keeper, even within the 18-yard box, it’s a problem.

2. Rio Tinto Stadium (Real Salt Lake)

They may not be as hyped as the fans in Seattle or Toronto, but RSL’s loyalists make Sandy, Utah, a true fortress (and the team has the home record to prove it).

3. BMO Field (Toronto FC)

Let’s be honest here: with capacity crowds a way of life on the north shore of Lake Ontario, this crowd changed the expectations for soccer crowds in North America. And with a season ticket waiting list of more than 10,000 fans, it’s not going anywhere any time soon.

4. The Home Depot Center (LA Galaxy)

They may be notoriously late to arrive, but the Galaxy faithful have always been one of the more vocal audiences in MLS. And with three different supporters groups spread out around the stadium, there is no place for an opposing player to hide.

5. Toyota Park (Chicago Fire)

Is there a stand in MLS as intimidating as the one housing Chicago’s Section 8? It's loud, it's organized, and it's impossible to ignore.

6. Dick’s Sporting Goods Park (Colorado Rapids)

While the altitude surely works in favor of DSG Park, it’s the close proximity of the supporters’ terrace behind the west goal that also gives the home team an edge.

7. Crew Stadium (Columbus Crew)

The consolidation of supporters groups into a single, raucous corner of Crew Stadium has had a dramatic effect on the atmosphere in Columbus. You won’t find a more unwelcoming spot from which to take a corner kick in all of MLS.

[inline_node:328566]8. PPL Park (Philadelphia Union)

The Sons of Ben may get all the press, but there is life in Chester beyond the River End. They were the new guys in 2010, but these fans already have a reputation.

9. RFK Stadium (D.C. United)

This is the original 12th Man of MLS. Unlike most stadiums, the club’s largest supporters groups are housed in the bouncing, sideline stands in full view of the TV cameras. Why hide the hardcore behind the goals?

10. Red Bull Arena (New York Red Bulls)

The South Ward brings the ruckus with its “only in New York” mix of Latin-percussion and witty interpolations of hip-hop, punk and terrace anthems. Add in the only full roof in MLS and the volume pumps up to 11.

The Rest

They may not have made the top 10, but the other stadiums in MLS have their intimidation factors, too. (Alphabetical by club.)

The Home Depot Center (Chivas USA)

The Goats' supporters' group may not have the numbers that their Home Depot Center roommates do, but make no mistake: There is no lack of passion—especially when they are playing the Galaxy.

Pizza Hut Park (FC Dallas)

Just as it does in Houston, the Texas sun works against Dallas’ visitors quite well. But the Inferno and the rest of the FC Dallas faithful do their part to turn up the heat

Robertson Stadium (Houston Dynamo)

It’s not just the Gulf Coast heat and humidity that make the Dynamo’s home hostile; the Texian Army and El Battalon do a fine job of making visiting teams feel unwelcome.

[inline_node:322387]CommunityAmerica Ballpark (Sporting Kansas City)

Kansas City may have a new name and home this year, but they'll still have the same loyal supporters behind them (and maybe a few more) in 2011. (Kansas City will move into a new venue, LIVESTRONG Sporting Park, in 2011.)

Gillette Stadium (New England Revolution)

Though the turf provides a homefield advantage for the Revs, you can’t count out the crowd as the Midnight Riders keep things interesting in The Fort.

Buck Shaw Stadium (San Jose Earthquakes)

Her capacity may be small, but Buck Shaw’s intimacy means a concentrated, intense crowd. The Casbah and the 1906 Ultras do their part to keep things lively.

Portland and Vancouver were excluded as the players polled have yet to play there in MLS competition.